Experimental evaluation of anechoic chambers

Antenna gain and radiation patterns, as well as radar cross sections of objects are measured in anechoic chambers. The chambers are used for convenience and to eliminate, as far as practical, sources of unwanted reflections. It would be useful if anechoic chambers could be categorized by a figure of merit which would predict their performance when antenna measurements are made. With this in mind, two methods of testing anechoic chambers, the traverse method and the pattern comparison technique, were applied to four different rooms. It is shown that the two methods do not give consistent results and it is concluded that no unique figure of merit can be assigned to an anechoic chamber.